The main aim of this study was the identification of possible routes for reaction mechanism for the pyrolysis of polyethylene. In this paper, a kinetic study of the pyrolysis of polyethylene is presented. The pyrolysis reactions were carried out in a six autoclave system using different temperatures and reaction times. It was analyzed if the direct conversion of plastic wastes into gaseous, liquid, and solid products was favored or if parallel reactions and/or reversible elementary steps should be considered. A theoretical model has been ajusted to experimental data. The kinetic parameters of polyethylene pyrolysis were estimated.